mikehende wrote: he recommend I try the Aphex Big Bottom unit as that is designed to punch the bass without increasing the audio level:
In that case, your speaker builder is (I am sorry to say and assuming he is in possession of all the facts) an idiot.
I have the Aphex Big Bottom - the real one, not just the software and it does a COMPLETELY different task. It adds harmonic distortion to the bass.
Hugh told you the answer right at the beginning - it's the bloody room. A garage is the WORST place to listen to anything! IT'S TOO SMALL!
We have a listening room that doubles as a movie theater. It's where I do mastering in stereo, 5.1 and 7.1 and where we watch completed films (and lately in C19 lockdown watch movies of course!) and it is acoustically treated. Bass traps adorn every corner. I spent an entire day measuring the room - and I happen to know what I am doing! It is many times larger than a bloody garage!
Without proper acoustic treatment, the second and third rows would get NO BASS AT ALL. With treatment, you hardly notice any difference.
When I am not playing at being a studio owner, I am a business consultant and this is a classic case of what I call 'Looking for magic zoom pills.'
Hugh gave you the answer - but it is not the answer you WANTED to hear!
Now stop waiting for that magic Zoom-Pill and listen to people that know what they are talking about - in this case, Hugh! It's the damn room (or rather that horrible garage).
Tell the wife that from now on, the living room is your new music studio and she can watch Eastenders on the lavatory!